The study of anoxic-oxic hybrid membrane bioreator (HMBR) treating landfill leachate

This paper is focusing on the investigation of a novel anoxic-oxic hybrid membrane bioreactor (A/O HMBR) for the treatment of landfill leachate. This new technique combined an efficient anoxic and oxic biological treatment process with a membrane filtration unit and has the advantages of simplifying pre-treatment facilities, relieving the loading of the subsequent treatment processes and optimizing the whole treatment process. The results showed that after two months of sludge acclimation, the average removal efficiency of COD, ammonia nitrogen and total nitrogen in the effluent from A/O bioreactor achieved 67%, 52.2% and 55.9%, respectively. Under the condition of COD volume loading of 0.84kgCOD/m³d, the average COD removal efficiency reached 81.8%. When the ammonia volume load was 0.68kg NH₃-N/m³d, 90% of the NH₃-N could be removed. In the case of reflux ratio of 300% and HRT of 2.5 days, the removal efficiency of COD, ammonia nitrogen and total nitrogen reached as high as 90.6%, 88.7% and 70.7%, respectively. These results demonstrated that the A/O-HMBR process is effective for removing COD and nitrogen from the leachate. Comparison of the three different processes, A/O-HMBR technology demonstrated higher removal efficiency than other two processes, especially in terms of ammonia nitrogen and total nitrogen removal. With regard to the requirement of inlet water quality for the following reverse osmosis (RO) process, the COD, ammonia nitrogen and total nitrogen concentration in the influent of the A/O HMBR should be maintained no greater than 3000, 1700 and 2300mg/L, respectively.